The priority document, German Patent Application No. 101 22 048 filed May 7, 2001, is incorporated by reference herein in its entirety.
The present invention relates to a method for the restraint of a vehicle occupant with the aid of a vehicle restraint system which comprises a windable three-point safety belt.
It is known to limit the belt force occurring in restraint systems by, for example, a deformable element, for example a torsion rod, being deformed in the event of an accident, whereby energy is dissipated and the belt force acting on the vehicle occupant is limited for a time.
It is an object of the present invention to provide a method for the restraint of a vehicle occupant with which the risk of injury is further reduced in the event of an accident.
According to an embodiment of the present invention, a method is provided that includes the steps of: measuring a reaction force (belt force) being transferred, in the event of an accident, from the safety belt to the vehicle occupant; and controlling a direct slackening of the safety belt such that the belt force does not exceed a pre-set maximum value.
In accordance with the invention, the load acting on the vehicle occupant is not passively limited, but the belt force which actually occurs is measured and the safety belt is slacked in dependence on this measured belt force so that the pre-set maximum value is not exceeded. Preferably, the maximum deceleration of the occupant occurs as early as possible with the aid of the safety belt and to maintain this maximum deceleration in the further development.
According to an embodiment of the present invention, a forward displacement of the vehicle occupant is also measured and the slackening of the safety belt is additionally controlled in dependence on this forward displacement, with the forward displacement preferably being measured in dependence on time so that a restraint of the vehicle occupant can take place in real time.
The slackening of the safety belt can take place by an actively influenceable braking device which acts on the safety belt. For example, an eddy current brake or a mechanical brake with frictional resistance can be provided.
The reaction force transferred from the safety belt to the vehicle occupant can preferably be measured in a reel of the safety belt or in a belt lock of the safety belt. It is also possible to determine the belt force in the region of a belt deflection.
The forward displacement of the vehicle occupant can be measured by determining the rotational movement of a spindle of a belt reel of the safety belt. Alternatively, it is possible to determine the forward displacement of the vehicle occupant by a radiation sensor, for example an infrared sensor, or a miniature camera arranged in the interior of the vehicle.
The weight of the vehicle occupant is preferably measured, for example by a device integrated in the vehicle seat, and the direct slackening of the safety belt may be additionally controlled in dependence on the weight measured. As a result, the belt forces be matched more precisely to the respective vehicle occupant.
A direct slackening of the safety belt is preferably only effected after the safety belt has been tensioned by a belt tensioning device.
The direct slackening of the safety belt can be controlled such that the pre-set maximum value of the belt force is reached as early as possiblexe2x80x94relative to the time of the impact of the accidentxe2x80x94and is maintained during the time of the impact of the accident.
The present invention also comprises various embodiments of a vehicle restraint system having the apparatus features described herein.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.